Drag device for antennas



April 27, 1943. w. P. LEAR 2,317,622

DRAG DEVICE FOR ANTENNAS Original Filed April 5, 1940 INVENTOR- W/lU/M/Pi 154/? A TTORNEY Patented Apr. 27, 1943 DRAG DEVICE? FOR ANTENNASWilliam P. Lear, Piqua, Ohio, assignor, by mesne assignments, to LearAvia, Inc., Piqua, Ohio, a corporation of Illinois Original applicationApril 5, 1940, Serial No.

327,984. Divided and this application January 22, 1942, Serial No.427,713

7 Claims.

This invention relates to reelable antenna systems, and moreparticularly to drag-type weighted antennae for aircraft. This case is adivision of my copending application Antenna drag cup, Serial No.327,984, filed April 5, 1940, now Patent 2,287,257 which is assigned tothe same assignee.

Generally there are two types of reelable radio antennae for aircraft.In one type, the antenna wire is drawn out and held suspended by astreamline weight, or lead fish. Such arrangement has the advantage ofaffording a substantial vertical antenna component for the efilcienttransmission and reception of radio waves. In the other type, the .endof the antenna wire is attached to a drag-cup or wind-sock. In thelatter case, the wire is held substantially horizontally by the windpressure on the drag-cup while the aircraft is in flight, giving only arelatively small vertical component.

The drag-type weighted antenna of the present invention combines theadvantages of both the prior types, and derives additional ones. Theinvention drag device combines both a drag-cup and a streamline weightin a novel manner. The

I weight is secured with the cup, and extends from a hollow sectionthereof with decreasing crosssection. The cup is preferably of resilientrubber, and is shaped so that a vacuum is created behind it when drawnthrough the air. Also, the resilient cup protects the aircraft from anydamage due to impacts by the weight.

The antenna is reeled out when the aircraft is in flight. The action ofgravity due to the weight portion, together with the drag on the cupportion by the wind pressure, effectively draws out the antenna. Whenthe antenna is unreeled to the desired length, the air drag on the cupcollapses it upon the weight portion. The crosssection of the cupagainst the Wind is thus decreased, resulting in a smaller aerodynamicresistance.

Also, the drag device of the invention maintains the antenna wire atabout a predetermined angle for given velocities of the aircraft. Theangle is determined by the vertical component of gravity acting on theweight and the extended wire, and the horizontal component of theaerodynamic drag on the device. Therefore, the antenna has anadvantageous vertical component for efficiently receiving andtransmitting radio signals. Since the drag-cup changes its shape incorrespondence with the speed of the aircraft, the drag horizontalcomponent will be substantially constant over normal speed changes, re-

sulting in a fairly constant antenna angle and operating efficiency.

These and further objects, advantages and capabilities of the presentinvention will become more apparent in the following description of apreferred embodiment thereof, illustrated in the drawing, in which:

Fig. 1 is an elevational view of the antenna drag device.

Fig. 2 is a cross-sectional view of the drag-cup of Fig. 1.

Fig. 3 illustrates an aircraft antenna unreeled with the drag device.

Fig. 4 is an elevational view of the antenna drag cup as it appears inflight conditions.

Referring to the drawing, the drag device of the invention comprises adrag-cup l9 having a hollow spherical section II. Cup H is preferablymade of a light-weight resilient rubber material. A taper-ed oregg-shaped weight I2 is secured to cup ID by eye-bolt l3 extendingcentrally through cup I0 and weight l2. A nut I4 is secured to the endof bolt [3, adjacent the far end of Weight l2. Tip 15 of bolt I3 ispeened over nut [4. The end of antenna wire I6 is secured to eye I! ofbolt l3 at a point adjacent extending tip l8 of cup It. A metal bushing29 surrounds the section of bolt 13 within cup l0.

The assembly of cup It with weight l2 'isaccomplished by tightening nutM on the threaded portion of bolt l3, and pressing head 2|. of the boltagainst the internal bushing 29. The juxtaposition of weight I2 againstcup to at central section H is along a flat section of relatively largearea. A suitable material for weight I2 is lead. The tapering of weightl2, diminishing in diameter as it extends away from cup It], is designedso as to least interfere with the drag action by cup l0 and hollowsection I l, and also be streamline for minimum air drag resistance.

As the drag assembly is moved through the air when craft 21 is inflight, a vacuum is developed behind cup II) at its hol low section IIproducing an aerodynamic force on the wire 16 and reel.

This force is an outward pull on .wire It, which assists in readilyunreeling the antenna by the drag device to any desired length. Weight12 serves to carry the drag device and antenna end beneath the aircraftby its gravity action. The combination of the gravity action of weight12 and the horizontal aerodynamic force on cup In constitutes asubstantial unreeling force acting on antenna wire l6.

As the speed of aircraft 21 increases, circular rim 25 of cup I!) iscompressed towards and about weight l2, as shown in Fig. 4. The dottedline position 25 in Fig. 4 indicates the normal (static) shape of dragcup In. Cup rim 25 may be partially collapsed as wire I6 is reeled outto the desired length. As rim 25 is collapsed towards the axis of cupI0, and about weight I2, the horizontal drag component thereon isgradually reduced, tending to stabilize the position of the drag cupassembly beneath the aircraft. Hence, during normal flight conditions,wire l6 extends at substantially a given angle below the aircraft. Theangle is dependent on the resilience of the cup [0, the weight of I 2and the air speed.

The angle which wire it forms with the axis of the aircraft is such thatas long as the aircraft is in flight, the vertical component of theantenna I is significant to efliciently receive or transmit radio waves.Furthermore, the angle, and therefore antenna efficiency, is stable overwidely varying conditions of flight due to'the compensating feature ofthe resilient cm).

Upon retraction of the antenna and drag-cup assembly, rubber tip l8abuts the opening in fairlead 26 arranged on the aircraft fuselage 21.Thus the shock of the impact is directly absorbed thereby on the fullretraction. Fairlead 25 is preferably of a ceramic material to .minimizeradio frequency losses. Another important feature is that the resilientcup l0 protects the aircraft from any damage which may occur by theweight portion it against the aircraft. The cup l0 surrounds the weightl2 and extends therefrom, so that the rubber cup touches the aircraftbody before the weight, and shields it from damage.

Although I have described a preferred embodi ment for carrying out theprinciples of my present invention, it is to be understood thatmodifications may be made therein without departing from the broaderspirit and scope thereof, as expressed in the appended claims.

I claim:

1. An antenna drag device comprising a resilient cup having an endportion for securement to an antenna wire, and a weight secured to saidcup-is coaxial alignment therewith and projecting therefrom in thedirection opposite said end portion.

2. An antenna drag device comprising a resilient cup having an endportion for securement to an antenna wire, and a weight secured to saidcup in coaxial alignment therewith and projecting therefrom in thedirection opposite said end portion, said weight extending from said cupwith narrowing cross-section.

3. An antenna drag device comprising a resilient rubber cup having anouter rim containing a hollow section and a tip extending away from saidsection, and a weight secured to said cup against the central part ofsaid section away from said tip.

4. An antenna drag device comprising a resilient rubber cup having anouter rim containing a hollow section and a tip extending away from saidsection, and a weight secured to said cup against the central part ofsaid section, said weight longitudinally extending from said cup withdiminishing cross-section, said rim being forced about said weight whensubjected to wind pressure.

5. An antenna drag device comprising a resilient rubber cup having ahollow portion, a streamline weighted section secured to said cup andextending therefrom with diminishing diameter, and means for holding thedevice in stable assembly comprising a bolt passing longitudinallythrough said cup and weight section.

6. An antenna drag device comprising a resilient rubber cup having ahollow portion, a weighted section secured to said cup against saidportion and extending therefrom with diminishing cross-secticn, andmeans for holding the device in stable assembly comprising a boltpassing longitudinally through said cup and weighted section, a bushingwithin said cup juxtaposed against the head of said bolt, and a nut onsaid bolt at the exterior end of said section.

7. An antenna drag-type device comprising a resilient rubber cup havinga circular outer rim containing a hollow spherical section and a tipextending away from said section, a weight having a flat portionjuxtaposed with the central part of said section and extendinglongitudinally therefrom with diminishing cross-section, and securingmeans extending axially through said cup and weight comprising a bushingimbedded in said cup coacting with a head on said means for holding saiddevice in stable assembly, said rim being forced about said weight whensubjected to wind pressure.

WILLIAM P. LEAR.

